The present invention relates generally to radio frequency receivers including television receivers and ancillary signal translating devices such as cable television converters and, in particular, to a remotely controllable television signal tanslating device having a sound muting capability.
Television signal translating devices such as cable television converters and the like are operative for converting a received television signal from one RF frequency to another RF frequency compatible with the signal processing characteristics of a conventional television receiver. For example, a cable television converter is typically operated in response to a remotely generated tuning control signal for selectively converting one of a plurality of cable television channels to a channel 3 or 4 television signal which is then supplied to the antenna inputs of a television receiver. The signal translation process is normally accomplished by initially converting the received cable television signal to an IF frequency and then suitably re-converting the IF signal to the channel 3 or 4 RF carrier frequency.
While remote tuning of cable television converters is generally well known in the art, various other desirable remote control features, e.g. sound muting, have heretofore not been available. With particular reference to remotely controllable sound muting, this feature is typically provided in a conventional television receiver by suitably controlling a switch or the like for grounding or otherwise rendering the audio baseband signal developed at the output of an FM demodulator unavailable to the speakers of the television receiver. It will be appreciated that this technique is not applicable to a signal translating device such as a cable television converter since the audio signal is not developed in such devices in a baseband form. Although a remotely operated trap, either at the IF or RF audio frequency, can be used to remove the sound carrier in the converter, this approach suffers from the disadvantage that only random noise is coupled to the audio processing circuits of the television receiver from the cable converter whereby a clearly audible noisy signal is produced.
It is therefore a basic object of the present invention to provide an improved remotely controllable sound muting system for use in association with a radio frequency receiver such as a television signal processing apparatus.
It is a further object of the invention to provide a remotely controllable sound muting capability for a television signal translating device which is effective in the IF and RF frequency spectrums.
It is yet another object of the invention to provide a remotely controllable sound muting capability for a television signal translating device wherein a frequency translated television signal is produced for application to a television receiver in a form inhibiting the production of any sound, including noise, by the receiver.